Misalignment/alignment compensation method, semiconductor lithography system, and method of semiconductor patterning

ABSTRACT

A misalignment/alignment compensation method for a lithography process includes the steps of: obtaining misalignment data associated with an alignment mark disposed on a substrate; and obtaining a compensation parameter by performing asymmetry compensation calculation on at least one of a first directional component of the misalignment data, which is associated with a first direction, and a second directional component of the misalignment data, which is associated with a second direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 14/546,645filed on Nov. 18, 2014, entitled “MISALIGNMENT/ALIGNMENT COMPENSATIONMETHOD, SEMICONDUCTOR LITHOGRAPHY SYSTEM, AND METHOD OF SEMICONDUCTORPATTERNING”, which claims priority to Taiwanese Application Nos.102142045 and 103122342, respectively filed on Nov. 19, 2013 and Jun.27, 2014; the entire contents of both which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a method for misalignment/alignmentcompensation, and more particularly to a misalignment/alignmentcompensation method, a system and a patterning method for asemiconductor process.

2. Description of the Prior Art

A semiconductor process refers to a process used to create a largenumber of semiconductor devices on a wafer using a multiple-stepsequence of photolithographic and chemical processing steps. In such ahighly-laminating process, when one of laminated layers is misaligned,the subsequent layers may thus be affected and further misaligned,thereby leading to failure of electrical connections among semiconductordevices and the layers, function losses, or short circuits. Therefore,precise and stable overlay control is a relatively important factor forprocess management to ensure yield of the semiconductor devices andefficiency of production.

For example, a conventional step-and-repeat aligner (i.e., a stepper orscanner) usually has an alignment sensor for detecting alignment marksthat are disposed at specific locations of a wafer before a lithographyexposure process, and an alignment offset of the aligner may becalculated according to the detected misalignment/alignment. If asubsequent rework process is required for the wafer, the overlay offsetmay be used to calibrate the aligner for ensuring optimal alignmentbetween patterns of a current layer (i.e., an upper layer) and aprevious layer (i.e., a lower layer).

Conventionally, the alignment or overlay offset is obtained by using theoverlay misalignment data in symmetry or independent calculation in bothX-direction and Y-direction, which is unable to satisfy asymmetryoverlay compensation requirements between the X-direction and theY-direction, especially in advanced process generation with singleorientation layout for resolution consideration. Referring to FIG. 1 asan example, in a common process of fabricating metal-oxide-semiconductor(MOS) devices, a required overlay distance or alignment margin x betweena contact hole 11, and an edge of a diffusion region 12, is differentfrom a required distance or alignment margin y between the contact hole11 and a poly gate 13. Since the overlay distance requirement oralignment margin x in the X-direction and the overlay distancerequirement or alignment margin y in the Y-direction are different (inFIG. 1, x<y), a theoretical weight of an offset in the X-directionshould be greater than that in the Y-direction. However, conventionalcalculations of the overlay offset uses symmetry or independentcalculation for compensations in the X-direction and the Y-direction,which is not suitable for a structure that has asymmetric alignmentrequirements in the X-direction and the Y-direction, and which mayresult in non-optimization of alignment or non-optimization of theoverlay offset after compensation. For example, a short circuit risk mayoccur between the contact hole 11 and the poly gate 13, as shown by anoverlap of a dotted circle and the poly gate 13 in FIG. 1.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide amisalignment/alignment compensation method that is suitable for anasymmetry alignment margin/overlay requirement structure, to therebyensure patterns of a current layer being optimally aligned with patternsof previous layers, satisfy alignment requirements for devices, and/orpromote optimization of alignment.

According to one aspect of the present invention, amisalignment/alignment compensation method for a lithography processcomprises:

-   -   obtaining misalignment data associated with an alignment mark        disposed on a substrate; and    -   obtaining a compensation parameter by performing asymmetry        compensation calculation on at least one of a first directional        component of the misalignment data, which is associated with a        first direction, and a second directional component of the        misalignment data, which is associated with a second direction.

Another object of the present invention is to provide a semiconductorlithography system that is adapted for implementing themisalignment/alignment compensation method of this invention, i.e.asymmetry compensation.

According to another aspect of the present invention, a semiconductorlithography system comprising:

-   -   an obtaining-and-storing unit configured to obtain and store        misalignment data associated with at least two alignment marks        disposed on the substrate;    -   a compensation parameter calculating unit configured to obtain a        compensation parameter by performing asymmetry compensation        calculation on at least one of a first directional component of        the misalignment data, which is associated with a first        direction, and a second directional component of the        misalignment data, which is associated with a second direction;        and    -   a lithography unit configured to perform a lithography process        on a substrate, and to perform alignment compensation according        to the compensation parameter.

Yet another object of the present invention is to provide a method ofsemiconductor patterning.

According to yet another aspect of the present invention, a method ofsemiconductor patterning is to be implemented utilizing a lithographictool, and comprises:

-   -   performing a lithographic alignment and patterning process on a        wafer layer for forming a lithographic pattern; and    -   determining position offset corrections based upon at least one        asymmetry tolerance factor involved in the lithographic        alignment and patterning process.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of embodiments withreference to the accompanying drawings, of which:

FIG. 1 is a top view illustrating a pattern with an asymmetry alignmentmargin/overlay requirement structure, and an alignment result usingsymmetry compensation;

FIG. 2 is a block diagram illustrating a semiconductor lithographysystem to implement a misalignment/alignment compensation methodaccording to the present disclosure;

FIG. 3 is a flow chart illustrating steps of a first embodiment of themisalignment/alignment compensation method according to the presentdisclosure;

FIG. 4 is a plot illustrating results of non-equal conversion using aproportional relationship equation;

FIG. 5 is a plot illustrating results of non-equal conversion using adifference equation;

FIG. 6 is a flow chart illustrating steps of a second embodiment of themisalignment/alignment compensation method according to the presentdisclosure;

FIG. 7 is a top view illustrating the pattern with an asymmetryalignment margin/overlay requirement structure, and an alignment resultusing asymmetry compensation;

FIG. 8 is a flow chart illustrating steps of a third embodiment of themisalignment/alignment compensation method according to the presentdisclosure; and

FIG. 9 is a flow chart illustrating steps of the third embodiment inanother form.

DETAILED DESCRIPTION

The compensation method for alignment control or overlay control of analigner 3 (see FIG. 2) according to the present disclosure is adaptedfor a fabrication process of semiconductor devices, in which analignment structure with asymmetry margin/tolerance exists among acurrent patterning layer and previous patterning layers (as shown inFIG. 1). The misalignment/alignment compensation method may ensure thata pattern of the current layer which has alignment marks thereon isoptimally aligned with a pattern of the previous layers, therebyenhancing alignment optimization of the semiconductor devices.

Referring to FIG. 2, the misalignment/alignment compensation method ofthis disclosure is performed by a misalignment/alignment compensationsystem 2.

The misalignment/alignment compensation system 2 includes areceiving-and-storing unit 21, a compensation parameter calculating unit22, an output unit 23, and a tolerance compensation unit 24.

The receiving-and-storing unit 21 receives and stores plural sets ofmisalignment data from a semiconductor substrate via, for example,direct scanning measurement or calculation.

It should be noted that the misalignment data may be measurement orcalculation results in polar coordinates (r, θ) or Cartesian coordinates(x, y). In this embodiment, the misalignment data are exemplified usingthe Cartesian coordinates, but the present invention should not belimited in this respect.

The receiving-and-storing unit 21 may be an ordinaryaddressing/positioning equipment, a misalignment measuring machine(e.g., a stepper, a scanner, etc.), or a storage device included in amisalignment measuring machine that is capable of receiving and storingraw misalignment data (x, y). The misalignment data may be obtained frommisalignment between alignment marks on the current patterning layer andthe previous patterning layers (e.g., the layers patterned before thecurrent layer) of the semiconductor substrate, or from comparisonbetween measured coordinates of the alignment marks and predeterminedcoordinates with respect to the substrate.

The compensation parameter calculating unit 22 includes a calculatorconfigured to perform asymmetry overlay compensation calculation onmultiple sets of the misalignment data that are stored in thereceiving-and-storing unit 21, thereby obtaining a compensationparameter. The compensation parameter calculating unit 22 may furtherinclude an X/Y asymmetry condition input member 221 for a user to inputasymmetry overlay alignment conditions (i.e., user-defined asymmetryconditions, which may be associated with tolerances/margins, orweightings) with respect to an X-direction and a Y-direction, so thatthe calculator may perform the asymmetry overlay compensationcalculation accordingly and obtain the compensation parameter.

In one embodiment, each set of the misalignment data is representedusing (x, y), where x is a value of the misalignment data in theX-direction (a first directional component), and y is a value of themisalignment data in the Y-direction (a second directional component).The compensation parameter calculating unit 22 may use the calculator toperform non-equal conversion on the first directional component x and/orthe second directional component y, thereby obtaining a set of converteddata (x′, y′) that corresponds to the set of the misalignment data (x,y). Then, the compensation parameter calculating unit 22 uses theconverted data (x′, y′) to perform compensation parameter calculation,thus obtaining the compensation parameter.

In another embodiment, the asymmetry condition input member 221 may beused for input of the user-defined asymmetry conditions for thealignment marks with respect to the X-direction and the Y-direction, andthe calculator may use the user-defined asymmetry conditions to directlyperform the compensation parameter calculation, thus obtaining thecompensation parameter. Note that the user-defined asymmetry conditionsmay be asymmetric tolerances/margins, asymmetric values specified in adevice specification, or asymmetric weighted values that are asymmetricbetween the X-direction and the Y-direction. The user-defined asymmetryconditions may be inputted in a form of a number, a ratio or apercentage. For example, the user-defined asymmetry conditions may beinputted as: (0.2, 0.1), 0.5(0.1/0.2) or 50%.

The compensation parameter calculating unit 22 may be a calculatingsystem built in the aforementioned stepper, scanner, or the misalignmentmeasuring machine, an independent computer system, or the misalignmentmeasuring machine, which may further convert the misalignment data (x,y) using the compensation parameter, to thereby obtain misalignmentresiduals via calculation.

The output unit 23 may be a computer system built in the aforementionedstepper, scanner or the misalignment measuring machine, or anindependent computer system, which is configured to output thecompensation parameter to an aligner 3, thereby enabling the aligner 3to perform asymmetry alignment compensation on the semiconductorsubstrate.

Referring to FIG. 3, the first embodiment of the misalignment/alignmentcompensation method according to this disclosure includes a raw dataacquiring step S21, a compensation calculating step S22 and acompensating step S23.

In step S21, the receiving-and-storing unit 21 obtains plural sets ofmisalignment data (x, y) that are associated with misalignment among thecurrent patterning layer and the previous patterning layers of thesemiconductor substrate processed with a lithography process includingphotoresist coating, aligning, exposing and developing, where x, y aremisalignment values in the X-direction and the Y-direction,respectively.

The semiconductor substrate may be a liquid crystal panel/display, asemiconductor wafer, etc., which may be applied to different uses. Inthis embodiment, the substrate is exemplified using a semiconductorwafer. The misalignment data (x, y) may be measurement results acquiredby the misalignment measuring machine measuring alignment marks thatoriginally exist on the wafer surface, and/or measuring overlay marksthat are formed on a laminated layer of the semiconductor wafer surfacevia a post-process. The raw misalignment data (x, y) thus acquired maybe stored in the receiving-and-storing unit 21 after beingmeasured/received thereby.

It should be noted that the aforementioned process is not limited tofabrication of integrated circuits (IC), and may be applied tofabrication of other devices having a structure in micron-scale ornano-scale, such as an optical system, a pattern of a photoreticle, aninspection pattern of a magnetic storage device, a flat panel display, aliquid crystal display, etc. The substrate may be a base material thatonly has a previous patterning layer (or bottom layer) with thealignment marks, or may be a base material that already has multiplelaminated layers.

In step S22, the compensation parameter calculating unit 22 performsnon-equal conversion on the misalignment data (x, y), to thereby obtainthe converted data (x′, y′). Note that the non-equal conversion isnon-equal between the X-direction and the Y-direction, and may be aconversion with respect to only one direction. Then, the compensationparameter calculation is performed using the converted data (x′, y′) tothereby obtain the compensation parameter.

Specifically, in step S22, the non-equal conversion is performed onplural sets of the misalignment data (x, y) to obtain plural sets of theconverted data (x′, y′) that satisfy: x′=x−a, y′=y−B, where A=±(S_(x)/2)or 0, B=±(S_(y)/2) or 0, and S_(x) and S_(y) are respectivelypredetermined tolerance values in the X-direction and the Y-direction.The predetermined tolerance values may be spec values (i.e., valuesspecified in a device specification) or acceptable tolerances/margins.

For details of step S22, the compensation parameter calculating unit 22performs non-equal conversion on the misalignment data (x, y) byelementary arithmetic operations, linear functional operations,polynomial operations or combinations thereof, to thereby obtain thecorresponding converted data (x′, y′).

In one example of step S22, the values x and y of the misalignment data(x, y) (i.e., the misalignment values respectively in the X-directionand the Y-direction) may be respectively and/or simultaneouslymultiplied by constants a and b (called a proportional relationshipequation) for converting the misalignment data (x, y) into the converteddata (x′, y′), where x′=ax, y′=by, a≠b, a>0 and b>0. Preferably, a≠b,and one of the constants a and b is equal to 1. In another example, oneof the values x and y of the misalignment data (x, y) may be added orsubtracted by a constant m or n, or the values x and y of themisalignment data (x, y) may be respectively added or subtracted by theconstants m and n (called a difference equation) for converting themisalignment data (x, y) into the converted data (x′, y′), where x′=x±m,y′=y±n and min. In addition, m≠0 and/or n≠0.

It should be noted that, since the aforementioned constants a, b, m andn are used to deform the misalignment data (x, y) for generatingasymmetry results, values thereof are arbitrary in theory. However, inconsideration of layouts and sizes of the devices, line widths and linespacing, the constants a and b are preferable to be greater than 0 andnot greater than 2, and the constants m and n are preferable to be notgreater than 10 nm.

The aforementioned built-in or independent compensation parametercalculating unit 22 performs the compensation parameter calculationusing the converted data (x′, y′), which is converted from themisalignment data (x, y), to thereby obtain the compensation parameter.The compensation parameter may be associated with wafer rotation, wafertranslation, wafer expansion, reticle rotation and magnification, etc.Since the compensation parameter calculation, which conventionally usesthe misalignment data (x, y) therein, is well-known to persons skilledin the art, details thereof are not described herein for the sake ofbrevity.

Finally, in step S23, the output unit 23 outputs the compensationparameter obtained in step S22 to the aligner 3 to serve as an alignmentvalue/alignment compensation value with respect to the substrate havingthe raw misalignment data, so as to calibrate the aligner 3.

Specifically, FIG. 4 illustrates results of non-equal conversion on theraw misalignment data (x, y) using the proportional relationshipequation, where x′=x×a and y′=y×b. Since the constant a is controlled tobe not equal to the constant b, asymmetric deformation may be generatedafter conversion in step S22. As an example, a region A of FIG. 4represents a conversion result in which the values x and y of the rawmisalignment data Z are respectively multiplied by the constants a and b(where a<b<1). Therefore, misalignments in both of the X-direction andthe Y-direction are processed to be better in the region A compared tothe original raw misalignment data Z. However, a variation of themisalignment data in the X-direction is processed to be even better thanthat in the Y-direction. Note that “better” is defined to be a directiontoward the origin (0, 0) herein, and “worse” is defined to be adirection away from the origin (0, 0) hereinafter. Therefore, when theconverted data that falls in the region A is used in compensationparameter calculation, the compensation parameter thus obtained may havea greater compensation weight in the Y-direction compared to that in theX-direction. In another example, a region F of FIG. 4 represents aconversion result in which the values x and y of the raw misalignmentdata Z are respectively multiplied by the constants a and b (wherea>b>1). Therefore, misalignments in both of the X-direction and theY-direction are processed to be worse in the region F compared to theraw misalignment data Z. However, a variation of the misalignment datain the X-direction is processed to be even worse than that in theY-direction. Therefore, when the converted data that falls in the regionF is used in compensation parameter calculation, the compensationparameter thus obtained may have a greater compensation weight in theX-direction compared to that in the Y-direction.

Table 1 lists relationships among regions A to F, lines G and H, theconstants a, b, the point Z (x, y), and comparisons between thevariations of the converted data (x′, y′) and the raw misalignment data(x, y) in the X-direction and the Y-direction according to FIG. 4.

TABLE 1 Relative variations Region/ x′, y′ relative to x, y of x′, y′Line Relationship x′ y′ x′ y′ A 1 > b > a Better Better Better Worse B1 > a > b Better Better Worse Better C b > 1 > a Better Worse BetterWorse D a > 1 > b Worse Better Worse Better E b > a > 1 Worse WorseBetter Worse F a > b > 1 Worse Worse Worse Better G a = 1 ConstantWorse/ Constant Worse/ Better Better H b = 1 Worse/ Constant Worse/Constant Better Better

FIG. 5 illustrates results of non-equal conversion on the rawmisalignment data (x, y) using the difference equation. As an example,converted data I(x′, y′) is a result of converting the raw misalignmentdata Z(x, y) by defining x′=x−m and y′=y+n, where m>0 and n>0.Therefore, misalignment of the converted I in the X-direction isprocessed to be better than that of the raw misalignment data Z in theX-direction. On the other hand, misalignment of the converted data I inthe Y-direction is processed to be worse. Therefore, when the converteddata I is used in compensation parameter calculation, the compensationparameter thus obtained may have a greater compensation weight in theY-direction compared to that in the X-direction.

Table 2 lists comparison results between variations of the converteddata I-P that are converted from the raw misalignment data Z usingdifferent constants m, n, and the raw misalignment data Z according toFIG. 5.

TABLE 2 x′, y′ relative to Relative variations x, y of x′, y′ Point x′cp. x y′ cp. y x′ cp. y′ y′ cp. x′ I Better Worse Better Worse J BetterConstant Better Constant K Better Better — — L Constant Worse ConstantWorse M Constant Better Constant Better N Worse Worse — — O WorseConstant Worse Constant

In order to have similar tendencies during conversions of themisalignment data (x, y) into the converted data (x′, y′), preferably,the conversion process is controlled to satisfy the same one of thefollowing relationships: x/x′>y/y′ and x/x′<y/y′, and satisfy x×y′≠y×x′,thereby causing all of the converted data (x′, y′) to have the samedeformation tendency. Moreover, in order for the asymmetry misalignmentcompensation to have a relatively higher contribution in the calculationprocess of the compensation parameter, preferably, the compensationcalculating step S22 is performed on at least half of the sets of theraw misalignment data (x, y).

It should be noted that, in the abovementioned first embodiment, boththe directional components x, y are exemplified to be positive (i.e.,the misalignment data (x, y) is located in a first quadrant). When themisalignment data (x, y) is located in another quadrant, thepositive/negative signs of the values x, y may be considered in thecalculation. In one example using the difference equation,x′=x+(x/|x|)×m and y′=y+(y/|y|)×n. In another example using theproportional relationship equation, x′=x×(x/|x|)×a and y′=y×(y/|y|)×b.Preferably, both of the constants a and b are greater than zero.

Furthermore, in order to ensure that the converted data (x′, y′) and thecorresponding misalignment data (x, y) are located in the same quadrant,when x>0, x is to be shifted by m (m>0), such that x′=x+m; and when x<0,x′ is configured to be x−m (m>0). Similarly, when y>0, y is to beshifted by n (n>0), such that y′=y+n; and when y<0, y′ is configured tobe y−n (n>0). In such a manner, a quadrant-change issue that may beencountered in step S22 and that results from the raw misalignment data(x, y) being close to the X-axis or the Y-axis may be avoided.

Referring to FIG. 6, the second embodiment of the misalignment/alignmentcompensation method according to this disclosure includes a raw dataacquiring step S31, an input step S32, a compensation calculating stepS33 and a compensating step S34.

In step S31, the receiving-and-storing unit 21 scans and stores pluralsets of misalignment data (x, y) that are associated with misalignmentsamong the alignment marks of the semiconductor substrate.

In step S32, the asymmetry overlay alignment conditions (i.e., theuser-defined asymmetry conditions) that are asymmetric between theX-direction and the Y-direction is inputted via the asymmetry conditioninput member of the compensation parameter calculating unit 22.

In step S33, the calculator of the compensation parameter calculatingunit 22 performs the compensation parameter calculation on themisalignment data (x, y) using the asymmetry conditions inputted via theasymmetry condition input member, to thereby obtain the compensationparameter.

Note that the user-defined asymmetry conditions may be asymmetrictolerances/margins, asymmetric spec values specified in a devicespecification, or asymmetric weighted values of misalignments of thealignment marks in the X-direction and the Y-direction for a singleexposure process, a single patterning process, a multi-exposure process,a multi-patterning process or a photoresist rework process. Theasymmetry condition may be a ratio or a weighting of spec tolerances ofthe raw misalignment data in the X-direction and the Y-direction (e.g.,X/Y=60/40), tolerances of the raw misalignment data in the X-directionand the Y-direction (e.g., |(X)|≤a or |(Y)|≤b), or a spec deviationvalue for the raw misalignment data between the X-direction and theY-direction (e.g., |(X)|−|(Y)|=k).

In one application, the asymmetry conditions may be inputted each timethe calculation of the compensation parameter is to be performed. Inanother application, the asymmetry conditions may be inputted only once,and the calculator may directly acquire the asymmetry conditions set forthe previous process to perform compensation parameter calculationwithout inputting the asymmetry conditions anew.

Finally, in step S34, the compensation parameter thus calculated isinputted into the aligner 3, to thereby use the compensation parameterfor calibration and compensation of the alignment/rework equipment.

Referring to FIG. 7, when the X-Y asymmetry compensation as described inthe first and second embodiment is applied to the example as illustratedin the prior section, a greater compensation weight may be acquired inthe X-direction, a larger overlay margin may obtained between thecontact hole 11 and the poly gate 13, and the short-circuit risk may beprevented.

The third embodiment disclosed herein uses the misalignment/alignmentcompensation method of this disclosure to serve as amisalignment/alignment control method of a lithography process.

Referring to FIG. 8, the third embodiment of this disclosure is a methodfor semiconductor patterning, and includes a loading step S41, analignment compensation calculating step S42, and a compensating stepS43.

In step S41, a semiconductor substrate that contains at least twoalignment marks on a surface thereof is coated with a photosensitivematerial layer, and is loaded on a lithography exposure unit. In thisembodiment, the lithography exposure unit is an exposure (processing)equipment that performs alignment operation on the semiconductorsubstrate.

In step S42, the asymmetry overlay compensation calculation that isasymmetric between the X-direction and the Y-direction is performed onthe misalignment data of the alignment marks, to thereby obtain thecompensation parameter.

In one implementation, the asymmetry overlay compensation calculationmay be performed by the compensation parameter calculating unit 22performing non-equal conversion that is non-equal between the firstdirectional component (i.e., in the X-direction) and the seconddirectional component (i.e., in the Y-direction) of the misalignmentdata, and then obtain the compensation parameter. In anotherimplementation, the compensation parameter calculating unit 22 maydirectly perform the compensation parameter calculation on themisalignment data using the user-defined asymmetry conditions of theX-direction and the Y-direction, to thereby obtain the compensationparameter. Details thereof are the same as those described in the firstand second embodiments, and are thus omitted herein for the sake ofbrevity.

In step S43, the compensation parameter is inputted into the exposure(processing) equipment, and is used for calibration and compensation ofalignment in an exposure and lithography process performed on thesemiconductor substrate by the exposure equipment.

In other words, referring to FIG. 9, in this embodiment, a lithographictool (e.g., the lithography exposure processing unit) is utilized toperform a lithographic patterning process on a wafer layer (i.e., thesemiconductor substrate), to thereby result in formation of alithographic pattern on the wafer layer. After an initial waferalignment, asymmetry (compensation) calculation may be performedaccording to the measured coordinates of the alignment marks and thepredetermined coordinates, or wafer photo-resistcoating/exposure/developing processes may be performed, followed byproceeding with overlay measurement to obtain raw misalignment data.Then, the alignment result is judged according to the raw misalignmentdata. When the alignment result is determined to be acceptable, thecompensation process is ended, and the wafer may be provided to asubsequent fabrication process (e.g., an etching process). When thealignment result is determined to be not acceptable, asymmetry(compensation) calculation may be performed to determine position offsetcorrections (i.e., the compensation parameters) based upon asymmetrytolerance factors (e.g., the asymmetry overlay compensation calculation,the user-defined asymmetry conditions, etc.) involved in thelithographic alignment process. Then, the lithographic tool performspositional control of the lithographic tool according to the positionoffset corrections thus determined. Note that lithographic patterningprocess may be performed/repeated in order to form differentlithographic patterns on different layers, and the asymmetry tolerancefactors for each lithographic patterning process are independent fromthose of other lithographic patterning processes.

In summary, the present disclosure obtains the compensation parameter byusing the user-defined asymmetry conditions between the X-direction andthe Y-direction for the alignment marks to directly perform asymmetryoverlay compensation parameter calculation on the misalignment data, orby first performing non-equal conversion between the X-direction and theY-direction on the misalignment data that is stored in thereceiving-and-storing unit, and then performing the compensationparameter calculation, to thereby satisfy alignment compensationrequirement for asymmetry overlay optimization/requirement. In such amanner, the pattern of the current layer may be optimally aligned withthe patterns of the previous patterning layers, thereby promotingoptimization of alignment and satisfying requirements for the devices.

While the present invention has been described in connection with whatare considered the most practical embodiments, it is understood thatthis invention is not limited to the disclosed embodiments but isintended to cover various arrangements included within the spirit andscope of the broadest interpretation so as to encompass all suchmodifications and equivalent arrangements.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A computer system for performing asymmetrycompensation calculation, comprising: an obtaining-and-storing unitconfigured to obtain and store misalignment data; and a compensationparameter calculating unit configured to obtain a compensation parameterby performing asymmetry compensation calculation on at least one of afirst directional component of the misalignment data, which isassociated with a first direction, or a second directional component ofthe misalignment data, which is associated with a second direction,wherein the asymmetry compensation calculation is performed according toa user-defined asymmetry condition that is asymmetric between the firstdirection and the second direction, and the user-defined asymmetrycondition is a plurality of asymmetric weighted values of alignmentmarks in x and y directions, and the user-defined asymmetry condition isdirectly dependent on device specification, device tolerance orspecification deviation value for device, wherein device is asemiconductor device formed on a fabricated wafer; the computer systemfor performing asymmetry compensation calculation includes amisalignment measuring machine, a stepper or scanner.
 2. The computersystem according to claim 1, further comprising an output unit which isconfigured to output the compensation parameter to an aligner.
 3. Thecomputer system according to claim 1, wherein the user-defined asymmetrycondition is in a form of a number, a ratio, a weighting or apercentage.
 4. The computer system according to claim 1, wherein theuser-defined asymmetry condition is associated with a difference using adifference equation with respect to the first direction and the seconddirection.
 5. The computer system according to claim 1, wherein thecompensation parameter is associated with wafer rotation, wafertranslation, wafer expansion, or reticle rotation and magnification. 6.A misalignment/alignment compensation system, comprising: areceiving-and-storing unit; and a compensation parameter calculatingunit comprising a calculator configured to perform asymmetrycompensation calculation, wherein the asymmetry compensation calculationis performed by a computer system that includes a misalignment measuringmachine, a stepper or scanner, according to a user-defined asymmetrycondition that is asymmetric between the first direction and the seconddirection, and the user-defined asymmetry condition is associated with adifference with respect to the first direction and the second directionand is directly dependent on device specification, device tolerance orspecification deviation value for device, wherein the device is asemiconductor device formed on a fabricated wafer.
 7. Themisalignment/alignment compensation system according to claim 6, whereinsaid compensation parameter calculating unit comprises an asymmetrycondition input member configured for input of a user-defined asymmetrycondition.
 8. The misalignment/alignment compensation system accordingto claim 6, wherein the user-defined asymmetry condition is asymmetricbetween the first direction and the second direction, and is associatedwith at least one of asymmetric tolerances/margins, asymmetric valuesspecified in a device specification, or asymmetric weighted values. 9.The misalignment/alignment compensation system according to claim 6,further comprising an output unit which is configured to output thecompensation parameter to an aligner.